The electroretinogram (ERG) has now been studied in many animals, including man; the origin of the ERG is quite well understood, and the link between the components of the ERG waveform and retinal structures is fairly well established. Despite this knowledge, the ERG has not emerged as a powerful clinical tool. One reason is that the components of the ERG interact nonlinearly; thus the analysis of the waveform by eye is a process of weak logical inference. Formal methods of non- linear analysis are required if this is to be surmounted. The only analytical method which can assure success is the use of the Volterra functionals as developed by Wiener and recently put into practice by Marmarelis. We propose to follow the schedule given below. 1. Establish that the human ERG can be represented by a small number of low order kernels with adequate sensitivity and signal-to-noise ratio. 2. Examine the modifications of the Wiener kernels caused by simple laboratory manipulations of a normal subject; e.g. dark adaptation or use of colored stimuli. 3. Set up a nonlinear ERG facility at the Doheny Eye Foundation. 4. Analyze select pathological cases for comparison by conventional clinical techniques and by nonlinear methods.